Hydrogen peroxide helicopter
Andrew Nowicki
streamlined shape to reduce their aerodynamic drag.
Large, low density payload, such as a large telescope
or a large greenhouse cannot be transported by the
launcher because it generates too much drag. Air
breathing engines and stratospheric balloons have
been used to reduce the problem, but they are far
from perfect. Air breathing engines are expensive,
have low thrust-to-weight ratio (about 8) and they
overheat in very thin air. Stratospheric balloons
are cheap but not reusable.
I believe that the best solution is to replace the
first stage of the rocket launcher with a helicopter
powered by hydrogen peroxide monopropellant turbines.
The turbines are placed in the tips of the helicopter
blades, so the propellant is compressed by the
centrifugal force like the roton propellant. The
helicopter flies through the atmosphere slowly, so
the aerodynamic drag of its rocket stages and its
payload can be ignored even if their shapes are not
streamlined. 90% hydrogen peroxide has density of
1400 kg/m^3, specific impulse of 148 seconds at sea
level, and exhaust gas temperature of 1015 K.
Andrew Nowicki
AN> The turbines are placed in the tips of the helicopter
AN> blades, so the propellant is compressed by the
AN> centrifugal force like the roton propellant.
Correction: I would rather place platinum catalyst
packs in the tips of the blades and move the turbine(s)
to the axis of rotation.
It seems that the helicopter must have two sets
of propellers: small ones for the troposphere
and big ones for the stratosphere. Perhaps the
best design is made of three propellers: one big
propeller placed between two small propellers
which counter the torque produced by the big
propeller.
Anvil
You will want to research articles on Rotary Rocket and
Hiller Helicopters. Consider that the air-breathing Hiller
will outperform the use of just hydrogen peroxide and was
itself of limited use.
http://www.rafmuseum.org.uk/milestones-of-flight/world/1959.html
The Kaman (I believe) still has the altitude record
for helicopters at 29,846 ft
That same year Kittinger rode a ballon to 76,400 ft and
an F-104C Starfighter reached 103,389 ft (at good speed).
Scale will be a problem.
Payload, speed, and altitude severe limitations.
Look at some of the balloon/skycrane concepts for ideas.
Boosters are hard to beat for lift, speed, and altitude.
-----
Another area that needs ideas and thoughts are Megalifters.
Something well beyond the C-5A, perhaps a jet airship.
Infrastructure is part of a booster's cost, and something
that could get sufficient mass at a usable altitude and
speed could be very useful. Also an ability to use
existing infrastructure (airports) and to use the remaining
part of the calender year delivering large container freight
rather than it and it's ground crews standing idle.
--
Anvil*
James Graves
>Andrew wrote:
>> It seems that the helicopter must have two sets
>> of propellers: small ones for the troposphere
>> and big ones for the stratosphere. Perhaps the
>> best design is made of three propellers: one big
>> propeller placed between two small propellers
>> which counter the torque produced by the big
>> propeller.
Yikes. Now you've really complicated the design.
If you have rockets on the rotor tips, you don't have much torque on
the fuselage which then needs to be countered.
>You will want to research articles on Rotary Rocket and
>Hiller Helicopters. Consider that the air-breathing Hiller
>will outperform the use of just hydrogen peroxide and was
>itself of limited use.
You will also want to review the news archives for Armadillo Aerospace.
They tried peroxide rocket tips on helicopter blades too.
They had some interesting failures.
At any rate...
You need to remember that getting up in altitude is only a fraction of
the problem. You are using most of your delta-V to get to orbital velocity.
The most efficient way to do that is to get _out_ of the atmosphere as
soon as you can. Sticking around inside the atmosphere means drag,
which leads to heat, which causes all kinds of problems.
Better to get out of the atmosphere, and accelerate to orbital speed
there. So you need a rocket anyway.
And since you're designing rockets, you might as well design a big dumb
booster for the first stage, to keep the design as simple as possible.
There have been a lot of people with a lot of ideas, but I have yet to
see the practicality of anything other than a rocket.
There are some secondary advantages to having something like a carrier
aircraft take you aloft, but these have to do with launch site location
and other factors. 50,000 ft of altitude doesn't really buy you much.
James Graves
Andrew Nowicki
> Consider that the air-breathing Hiller will outperform
> the use of just hydrogen peroxide and was itself of limited use.
The air breathing helicopter outperforms
the hydrogen peroxide helicopter only in one
respect: it consumes less fuel. The hydrogen
peroxide helicopter can fly to a higher altitude.
> Scale will be a problem.
Yes. This is the only flaw. The total area of the
helicopter has to be 10^4 square meters to lift
a 100 ton launcher to the altitude of 30 km.
> Payload, speed, and altitude severe limitations.
> Look at some of the balloon/skycrane concepts for ideas.
> Boosters are hard to beat for lift, speed, and altitude.
You do not understand the problem. The main
advantage of the helicopter is that it can
lift the launcher and payload slowly.
Lawrence Gales
On Sat, 17 Jul 2004, James Graves wrote:
> Date: Sat, 17 Jul 2004 17:55:26 +0000 (UTC)
> From: James Graves <ans...@typhoon.xnet.com>
> Reply-To: ans...@xnet.com
> To: sci-spa...@moderators.isc.org
> Newsgroups: sci.space.tech
> Subject: Re: Hydrogen peroxide helicopter
------------------------------
You might check out Len Cormier's Space Van 2008:
http://www.tour2space.com/sv2008/sv2008.htm
Len claims a number of advantages in *slowly* getting an orbiter to a high
altitute (about 70,000 feet) and then releasing it at a moderate speed,
about 350 mph:
- Greatly reduced structural weight due to
o Not having to fight your way at high speed through the lower
atmosphere (remember the shuttle would tear itself to pieces if it
did not throttle down to 65% around 40,000 feet)
o Not having to have strength in as many directions as its attitude
is always nearly horizontal
o Less need for streamlining and thus more efficient packaging
- Greatly reduced chamber pressues (e.g., 1400 psi vs 3000 psi) leading
to *much* longer engine life and reduced costs
- Greatly reduced mass ratio: if we compare SSME (ground launch) with
RL-10s, the MR reduces from 9.5 to between 6.5 and 7 --- a huge
difference
- A much smaller minimum size vehicle: 80-100 tons versus 500-1000 tons
I would say that slow airlaunch to a very high altitude has a very large
advantage
-- Larry
Andrew Nowicki
> If you have rockets on the rotor tips, you don't have much torque on
> the fuselage which then needs to be countered.
> You will also want to review the news archives for Armadillo Aerospace.
> They tried peroxide rocket tips on helicopter blades too.
This idea does not make sense because
the thrust produced by the rotor is about
the same as the thrust produced by the
rockets. The rotor does not serve any
purpose; it is merely parasitic weight.
> You need to remember that getting up in altitude is only a fraction of
> the problem. You are using most of your delta-V to get to orbital velocity.
>
> The most efficient way to do that is to get _out_ of the atmosphere as
> soon as you can. Sticking around inside the atmosphere means drag,
> which leads to heat, which causes all kinds of problems.
If you have to use a rocket to get through the
atmosphere, you have to fly through the
atmosphere quickly. If you can use the hydrogen
peroxide helicopter, there is no reason to fly
through the atmosphere quickly which means
that your rocket and payload can have any shape
and volume. In particular, your rocket can have
very big, frail, spherical tank filled with
liquid hydrogen. Its thermal insulation does not
have to be strong so it can be cheap and lightweight.
> And since you're designing rockets, you might as well design a big dumb
> booster for the first stage, to keep the design as simple as possible.
Yes, in the short term nothing can beat the
big dumb booster. The hydrogen peroxide
helicopter is more complex, but its specific
impulse and thrust-to-weight ratio are one
order of magnitude greater.
> There have been a lot of people with a lot of ideas, but I have yet to
> see the practicality of anything other than a rocket.
You sound like a typical rocketeer. If the
same mentality prevailed in the computer
industry, Intel CEO would say: "I have yet to
see the practicality of anything other than
the 286 processor." There is plenty of new,
promising, but untested ideas. They are posted
at: http://www.islandone.org/LEOBiblio/
> There are some secondary advantages to having something like a carrier
> aircraft take you aloft, but these have to do with launch site location
> and other factors. 50,000 ft of altitude doesn't really buy you much.
50,000 ft of altitude is worth a lot if you
fly slowly. Separation with the fast flying
aircraft in the atmosphere is difficult.
Pegasus does it, but it is a small launcher.
Ash Wyllie
>Anvil wrote:
>> Consider that the air-breathing Hiller will outperform
>> the use of just hydrogen peroxide and was itself of limited use.
>The air breathing helicopter outperforms
>the hydrogen peroxide helicopter only in one
>respect: it consumes less fuel. The hydrogen
>peroxide helicopter can fly to a higher altitude.
The limiting factor for helo altitude is not power, but 1) air density or
2) local speed of sound.
>> Scale will be a problem.
>Yes. This is the only flaw. The total area of the
>helicopter has to be 10^4 square meters to lift
>a 100 ton launcher to the altitude of 30 km.
57m blades are going to be a problem. Worse, to even the lift per disk
section, you will need to put a twist in the blades. Look at the blades of the
Osprey versus the bladers of a helocopter.
>> Payload, speed, and altitude severe limitations.
>> Look at some of the balloon/skycrane concepts for ideas.
>> Boosters are hard to beat for lift, speed, and altitude.
>You do not understand the problem. The main
>advantage of the helicopter is that it can
>lift the launcher and payload slowly.
You have never spent much time around helicopters.
-ash
Cthulhu for President!
Why vote for a lesser evil?
Andrew Nowicki
> Scale will be a problem.
Andrew Nowicki wrote:
> Yes. This is the only flaw. The total area of the
> helicopter has to be 10^4 square meters to lift
> a 100 ton launcher to the altitude of 30 km.
Ash Wyllie wrote:
> 57m blades are going to be a problem. Worse, to even
> the lift per disk section, you will need to put a
> twist in the blades. Look at the blades of the
> Osprey versus the bladers of a helocopter.
Yes, the 57m blades would be far too big.
The big helicopter should have many small
blades and small turbines.
Andrew Nowicki
> You might check out Len Cormier's Space Van 2008:
>
> http://www.tour2space.com/sv2008/sv2008.htm
>
> Len claims a number of advantages in *slowly* getting an orbiter to a high
> altitute (about 70,000 feet) and then releasing it at a moderate speed,
> about 350 mph:
> - Greatly reduced structural weight due to
> o Not having to fight your way at high speed through the lower
> atmosphere (remember the shuttle would tear itself to pieces if it
> did not throttle down to 65% around 40,000 feet)
> o Not having to have strength in as many directions as its attitude
> is always nearly horizontal
> o Less need for streamlining and thus more efficient packaging
> - Greatly reduced chamber pressues (e.g., 1400 psi vs 3000 psi) leading
> to *much* longer engine life and reduced costs
> - Greatly reduced mass ratio: if we compare SSME (ground launch) with
> RL-10s, the MR reduces from 9.5 to between 6.5 and 7 --- a huge
> difference
> - A much smaller minimum size vehicle: 80-100 tons versus 500-1000 tons
These are very good arguments!
Just two days ago I looked at this web site
and chatted with Len via email but I missed
this part. I would add one more argument:
Upper stage hydrogen tanks can be big, flimsy
spherical tanks with cheap, fluffy insulation.
> I would say that slow airlaunch to a very high altitude has a very large
> advantage
Atmospheric pressure drops about 4 times for
every 10 km of increased altitude. If you are
not launching raw eggs, 30 km should be enough :-)
Henry Spencer
Andrew Nowicki <and...@nospam.com> wrote:
>> They tried peroxide rocket tips on helicopter blades too.
>
>This idea does not make sense because the thrust produced by the rotor
>is about the same as the thrust produced by the rockets.
No, wrong. Please learn something about aerodynamics. The rocket thrust
only has to counteract the drag of the rotor blades, while the rotor
thrust is produced by the blades' lift. Asserting that rotor thrust is
about the same as rocket thrust is asserting that the rotor blades' L/D is
around 1. But at subsonic speeds, the L/D of a good airfoil design is
more like 100... although issues like tip effects reduce that considerably
in a real design.
Moving large masses of air slowly produces much more thrust -- for the
same amount of energy -- than moving a small mass of exhaust jet quickly.
Various complications intervene if the air is already moving rapidly past
you, but at low speeds, using a rotor wins big over a rocket. This is why
small, slow aircraft continue to use propellers, and the dominant engine
type for big subsonic aircraft is the turbofan, which uses a small turbine
core to spin a large fan -- essentially a high-speed ducted propeller.
The key question of a rocket-powered rotor is not whether it produces more
thrust at the start, but whether it gains you enough in total -- bearing
in mind that launchers want to accelerate very rapidly and that propeller
efficiency drops off badly as speeds rise -- to be worth its mass. Gary
Hudson said that for the classical Roton design, the bottom line on rotor
lift was about neutral for ascent -- no big gain, no big loss -- with the
main benefits being its other roles: drag device during reentry, lift
device for landing, and centrifugal pump for powered flight.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert | he...@spsystems.net
Anthony Garcia
"Lawrence Gales" <lar...@u.washington.edu> wrote in message
news:Pine.WNT.4.58.0407172228370.1384@your-kgj38sd53j...
[snip]
> You might check out Len Cormier's Space Van 2008:
>
> http://www.tour2space.com/sv2008/sv2008.htm
>
> Len claims a number of advantages in *slowly* getting an orbiter to a
high
> altitute (about 70,000 feet) and then releasing it at a moderate speed,
> about 350 mph:
> - Greatly reduced structural weight due to
> o Not having to fight your way at high speed through the lower
> atmosphere (remember the shuttle would tear itself to pieces if
it
> did not throttle down to 65% around 40,000 feet)
Unless you have a carrier aircraft bringing the launch vehicle up to
altitude you're trading off one sticky problem for another. You still
must use an oxidiser, if you expect the launch vehicle to be airbreathing
until using rocket propulsion you have the issue of added weight unless
you jettison something.
> o Not having to have strength in as many directions as its
attitude
> is always nearly horizontal
Now you have TWO structural problems instead of one. You must still have
the strength to withstand the acceleration when the rocket is thrusting
(2-7+G plus dynamic loading) AND you must have the horizontal strength to
withstand the structural load of being hoisted to altitude (probably 2-5G
plus dynamic loading) and this horizontal lift must be performed while
fueled
> o Less need for streamlining and thus more efficient packaging
How high do you expect to lift this thing slowly. Unless its up to
~200,000ft+, you are still going to have big aerodynamics problems.
> - Greatly reduced chamber pressues (e.g., 1400 psi vs 3000 psi)
leading
> to *much* longer engine life and reduced costs
Why do you select the particular value's you select for chamber pressure?
> - Greatly reduced mass ratio: if we compare SSME (ground launch) with
> RL-10s, the MR reduces from 9.5 to between 6.5 and 7 --- a huge
> difference
This mass ratio only counts if you forget the carrier and you find that
you will have a greatly reduced total mass to orbit.
> - A much smaller minimum size vehicle: 80-100 tons versus 500-1000
tons
> I would say that slow airlaunch to a very high altitude has a very large
> advantage
Debateable
James Graves
>The key question of a rocket-powered rotor is not whether it produces more
>thrust at the start, but whether it gains you enough in total -- bearing
>in mind that launchers want to accelerate very rapidly and that propeller
>efficiency drops off badly as speeds rise -- to be worth its mass. Gary
>Hudson said that for the classical Roton design, the bottom line on rotor
>lift was about neutral for ascent -- no big gain, no big loss -- with the
>main benefits being its other roles: drag device during reentry, lift
>device for landing, and centrifugal pump for powered flight.
Armadillo had significant problems with controlling the pressure of the
feed lines to the rockets on the tips of their rotor.
I would be interested in learning how RR was able to cope with this, and
have such well-controlled flights.
But I suppose that's one of the bits of precious IP left over from the
company's demise, and it is sitting in somebody's drawer, doing no one
any good right now.
James Graves
Andrew Nowicki
JG> If you have rockets on the rotor tips, you don't
JG> have much torque on the fuselage which then needs
JG> to be countered.
Andrew Nowicki wrote:
AN> This idea does not make sense because the thrust
AN> produced by the rotor is about the same as the
AN> thrust produced by the rockets. The rotor does not
AN> serve any purpose; it is merely parasitic weight.
Henry Spencer wrote:
HS> No, wrong. Please learn something about aerodynamics.
HS> The rocket thrust only has to counteract the drag of
HS> the rotor blades, while the rotor thrust is produced
HS> by the blades' lift. Asserting that rotor thrust is
HS> about the same as rocket thrust is asserting that the
HS> rotor blades' L/D is around 1. But at subsonic speeds,
HS> the L/D of a good airfoil design is more like 100...
..for the best gliders
HS> Moving large masses of air slowly produces much more
HS> thrust -- for the same amount of energy -- than moving
HS> a small mass of exhaust jet quickly. Various complications
HS> intervene if the air is already moving rapidly past you,
HS> but at low speeds, using a rotor wins big over a rocket.
We are talking about a helicopter that has enough thrust to
lift a rocket launcher. Suppose that the total rotor area
of the helicopter is 10^4 m^2 = one hectare -- a pretty big
helicopter. If the launcher weighs 100 tons and it is lifted
to the altitude of 30 km, the thin air will rush down through
the rotor at about 100 m/s. You cannot get much bigger
lift-to-drag ratio than one when the air moves down at the
speed of 100 meters per second. Are you suggesting to make a
helicopter having the total rotor area much bigger than one
hectare?
HS> This is why small, slow aircraft continue to use
HS> propellers, and the dominant engine type for big subsonic
HS> aircraft is the turbofan, which uses a small turbine core
HS> to spin a large fan -- essentially a high-speed ducted
HS> propeller.
This is good argument in favor of using an airplane propelled
by small rocket engine instead of the helicopter propelled
by the hydrogen peroxide turbines. The airplane wings have much
higher L/D ratio than the helicopter rotors. This means that
the airplane needs less thrust to move it forward than the
thrust needed to rotate the helicopter's rotor. On the other
hand, the airplane hauling the 100 ton rocket launcher has to
fly rather fast. If its wingspan is 100 meters and its final
altitude is 30 km, its minimum speed is about 100 m/s. The
rocket launcher must be streamlined to survive such a high
speed and it may be damaged when it separates from the airplane.
I am skeptical about feasibility of an airplane having wingspan
greater than 100 meters -- airplanes do not scale up well.
HS> The key question of a rocket-powered rotor is not whether
HS> it produces more thrust at the start, but whether it gains
HS> you enough in total -- bearing in mind that launchers want
HS> to accelerate very rapidly and that propeller efficiency
HS> drops off badly as speeds rise -- to be worth its mass.
The opposite is true -- read the Len Cormier's comments in
the other thread:
"Hydrogen peroxide helicopter (and Len Cormier's Space Van)"
HS> Gary Hudson said that for the classical Roton design,
HS> the bottom line on rotor lift was about neutral for ascent
HS> -- no big gain, no big loss -- with the main benefits being
HS> its other roles: drag device during reentry, lift device
HS> for landing, and centrifugal pump for powered flight.
Roton is a different animal -- it hauls its rotor all the way
to orbit.
______________________________________________________________
The main problem is the scale of the helicopters and the
airplanes. The thin air can barely support the weight of the
100 ton launcher. If hydrogen balloons were durable they would
be more economical than the helicopters and the airplanes.
Does anyone really need big, monolithic satellites and big
rocket launchers? It seems that satellites of any size can be
assembled in orbit by telemanipulators. It would be cheaper to
use a small, reusable rocket launcher than the big, expendable
launcher.
Len
> "Lawrence Gales" <lar...@u.washington.edu> wrote in message
> news:Pine.WNT.4.58.0407172228370.1384@your-kgj38sd53j...
> [snip]
> > You might check out Len Cormier's Space Van 2008:
> >
> > http://www.tour2space.com/sv2008/sv2008.htm
> >
> > Len claims a number of advantages in *slowly* getting an orbiter to a
> high
> > altitute (about 70,000 feet) and then releasing it at a moderate speed,
> > about 350 mph:
> > - Greatly reduced structural weight due to
> > o Not having to fight your way at high speed through the lower
> > atmosphere (remember the shuttle would tear itself to pieces if
> it
> > did not throttle down to 65% around 40,000 feet)
>
> Unless you have a carrier aircraft bringing the launch vehicle up to
> altitude you're trading off one sticky problem for another. You still
> must use an oxidiser, if you expect the launch vehicle to be airbreathing
> until using rocket propulsion you have the issue of added weight unless
> you jettison something.
You don't seem to get it.
Oxidizer that is cheap and that you get rid of is not
a "sticky" problem. Nor are the tanks, which stay
with the "kite" stage. In fairness to the context
of your comment, the kite stage is a form of a
carrier aircraft--but much cheaper and with important
differences.
You're right, airbreathing is quite inappropriate
for short duration flights spanning large altitudes.
Nothing is jettisoned--as in "thrown away." The
lightweight propellant tanks stay with the kite
stage and are easily recovered and used again.
Whether or not the rocket engines used for climb
stay with the kite or the orbiter is an option
for the current design. Thrust-to-weight builds
up from about 0.4 at takeoff to about 1.2 at
separation, which is appropriate for ballistic
flight after separation.
>
> > o Not having to have strength in as many directions as its
> attitude
> > is always nearly horizontal
>
> Now you have TWO structural problems instead of one. You must still have
> the strength to withstand the acceleration when the rocket is thrusting
> (2-7+G plus dynamic loading) AND you must have the horizontal strength to
> withstand the structural load of being hoisted to altitude (probably 2-5G
> plus dynamic loading) and this horizontal lift must be performed while
> fueled
>
Loads are far less. Captive lifting loads are not much
over 1g, and initial acceleration loads are less. With
allowance for dynamic loads and factor of safety,
3 g's ultimate design factor is appropriate. During
captive fllight these loads are carefully distributed,
and the orbiter aerodynamic surfaces carry none of
these loads. More importantly, panel flutter is not
a problem at low dynamic pressures. The orbiter never
sees dynamic pressures higher than those typical of a
light plane. After separation, loads are more like a
VTO launch system taking off in very low density air.
The dimensions of the kite system are such that there
are very few constraints on the size and shape of the
orbiter. This is another important advantage of the
kite approach.
> > o Less need for streamlining and thus more efficient packaging
>
> How high do you expect to lift this thing slowly. Unless its up to
> ~200,000ft+, you are still going to have big aerodynamics problems.
>
At the beginning of acceleration, 21,300 m (70,000 ft)
is very relieving. The orbiter climbs ballistically
from this point, with dynamic pressure dropping off.
Peak dynamic pressure occurs during initial climb,
with a tradeoff of climb efficient speed versus
limitations of the fabric covered truss structure
used in the kite stage. Eventually you have to be
much higher--as you point out. However, we never
see high dynamic pressure anywhere during the flight.
By the time we reach orbital speeds, we are probably
above 120 km (nearly 400,000 ft.).
> > - Greatly reduced chamber pressues (e.g., 1400 psi vs 3000 psi)
> leading
> > to *much* longer engine life and reduced costs
>
> Why do you select the particular value's you select for chamber pressure?
>
We would derate the Aerojet/Kuznetsov AJ-26/NK-33
to 80 percent to greatly increase lifetime. These
are specifics for this engine. We have other
candidate propulsion concepts in mind.
> > - Greatly reduced mass ratio: if we compare SSME (ground launch) with
> > RL-10s, the MR reduces from 9.5 to between 6.5 and 7 --- a huge
> > difference
>
> This mass ratio only counts if you forget the carrier and you find that
> you will have a greatly reduced total mass to orbit.
>
Stage mass ratio is what is important for performance.
Gross mass is a poor indicator of costs--which is
what the game should be about. Payload to orbit
and the cost of getting the payload to orbit--as
well as cost per flight--are the important parameters.
> > - A much smaller minimum size vehicle: 80-100 tons versus 500-1000
> tons
>
>
>
> > I would say that slow airlaunch to a very high altitude has a very large
> > advantage
>
> Debateable
While you debate, we'll go to orbit--but,
admittedly, only with financial support.
I like this news group. You can almost always
count on a straight man.
Best regards,
Len (Cormier)
PanAero, Inc.
x...@tour2space.com (change x to len)
http://www.tour2space.com
Greg D. Moore (Strider)
"Henry Spencer" <he...@spsystems.net> wrote in message
news:I19Ks...@spsystems.net...
>
> The key question of a rocket-powered rotor is not whether it produces more
> thrust at the start, but whether it gains you enough in total -- bearing
> in mind that launchers want to accelerate very rapidly and that propeller
> efficiency drops off badly as speeds rise -- to be worth its mass. Gary
> Hudson said that for the classical Roton design, the bottom line on rotor
> lift was about neutral for ascent -- no big gain, no big loss -- with the
> main benefits being its other roles: drag device during reentry, lift
> device for landing, and centrifugal pump for powered flight.
You know, it just dawned on me... I don't think SS1's "shuttlecock" design
is all that far from Rutan's rotor on the grand scale.
Hmm, interesting. (at least to me. :-)
James Graves
comments/questions:
What is the TPS? The slides imply they're not trying for a lifting
reentry. But a cheap, reliable throwaway heatshield isn't going to work
for that design, I don't think. Too much area to cover. Are we back to
RCC for the leading edges? We've all seen how well that works.
I think the 1st stage ascent engine(s) should be part of the gondola.
Is there any reason to carry them up to orbit and back? The attachment
between the orbiter and gondola has to take that kind of stress anyway.
A kite that size is going to be very unwieldly for ground handling.
I'm not sure what would be more practical. It might be easier to keep a
parafoil flat and not flopping around in the breeze than a more rigid
glider.
Related to that...
The SV2008 is also more sensitive to wind conditions. This could cause
launch window problems. Ideally, you'd have a giant circle, with the
winch in the center, so that you could launch into the wind in any
direction.
That's the main drawback to a low wing loading. No easy way to escape
this, AFAICS.
James Graves
John Carmack
> You do not understand the problem. The main
> advantage of the helicopter is that it can
> lift the launcher and payload slowly.
How is lifting the launcher and payload slowly through the lower
atmosphere an advantage? The launcher is going to have to throttle up
to actually boost after the helicopter lifting is done, so it will
still see the highest G and vibration loads later in the flight.
Rotors seem to be a big win for descent, because drag is good at that
point, but the case is a lot dodgier for ascent. The Isp improvement
falls off fast with speed, and you aren't likely to be able to exceed
supersonic at all with it (although Rotary Rocket claimed improvements
up to M1.25 or so), so it really isn't that hard to have a phenomenal
ground Isp not actually help across the entire trajectory. I'm still
on the fence about it, but it certainly adds complexity over just
boosting with rocket engines. Slinging a few sets of rotor blades off
the test stand was an educational experience.
The largest advantage to using rotors may be to keep ground noise down
significantly over pure rocket thrust. A modest sized orbiter with
rotor landing could land at any helipad, and even fairly large
vehicles could take off from conventional airports without needing
blast deflectors and huge sound clearances.
John Carmack
www.armadilloaerospace.com
Andrew Nowicki
> How is lifting the launcher and payload slowly
> through the lower atmosphere an advantage?
Probably the biggest advantage of lifting a rocket
launcher above dense part of the atmosphere with
a slow aircraft is the ability to use a very small
rocket launcher. A very small, reusable rocket
launcher is cheaper than any other launcher if you
use it frequently. The upper stage of the launcher
does not have to be streamlined, so it maybe shaped
like the conical reentry capsule.
It is not clear which aircraft is the best.
Hydrogen peroxide helicopter is the slowest.
Rocket plane may be the cheapest. Len Cormier's
rocket propelled kite may be difficult to
control during takeoff and landing.
A versatile canadian telerobot named Dextre will
be probably launched in December 2007 to repair
the Hubble Space Telescope. Another Dextre will
be launched later to service the International
Space Station. These telerobots will be idle most
of the time, so they can be used for other tasks,
for example to assemble large satellites from
small components launched by the very small,
reusable rocket launcher.
Len
> John Carmack wrote:
>
> > How is lifting the launcher and payload slowly
> > through the lower atmosphere an advantage?
>
structure and aerodynamic loads on the structure.
There is not likely to be much gain with respect
to thrust loads.
The potential gains of getting to high altitude
"gently" stem from the relief from panel flutter
and from aerodynamic loads and load distribution. Even
VTO ELV's are sensitive to "q x alpha." Lifting
reentry followed by horizontal approach and landing
does not have to involve prohibitive mass penalties.
However, if the lifting provisions have to survive
much higher dynamic pressure during climb and acceleration,
then the aero structure can be quite heavy.
An exception was our 1971 "Windjammer" that became
the Boeing RASV. This type of space transport is
designed for horizontal takeoff, horizontal climb
and horizontal initial acceleration. Initial thrust-
to-system-mass might be only about 0.7--thereby saving
propulsion system mass and avoiding some of the aft
c.g. balancing problems in the empty condition. With
relieving load from LOX in the wings, wing mass might
only be about twice what it would be for LOX tanks
alone. This also results in low planform laoding with
resultant lower peak temperatures--which helps to attain
the required mass ratio and further reduces peak reentry
temperatures--etc.
Each design concept must adhere to a well integrated
design approach. There are different solutions, but
each approach must be well thought out with consistent
design philosophy. Superficial parametric studies--as
distinguished from detail design/analysis studies of
specific concepts--usually lead to misleading conclusions.
For example, some studies of HTOL vehicles have been made
by VTOL advocates who merely turned a VTO vehicle on its
side, added wings and made the system takeoff horizontally.
These studies were entirely misleading by not adjusting
T/W to proper values and by not taking advantage of such
aircraft-design concepts as relieving load, etc.
I have made other recent posts on this thread that seem
to have gotten lost.
Henry Spencer
John Carmack <jo...@idsoftware.com> wrote:
>The largest advantage to using rotors may be to keep ground noise down
Possibly... although options for quieting rocket engines have not really
been explored much, and there are some hints that there might be a lot of
improvement to be had there with modest effort.
Henry Spencer
Andrew Nowicki <and...@nospam.com> wrote:
>A versatile canadian telerobot named Dextre will
>be probably launched in December 2007 to repair
Correction: to *attempt* to repair Hubble. Friends familiar with
Dextre's technology say this would be a high-risk mission. It's better
than older robots, but it's still nowhere near what you'd need to have
high confidence of a successful Hubble servicing job.
Henry Spencer
Andrew Nowicki <and...@nospam.com> wrote:
>HS> ...Asserting that rotor thrust is
>HS> about the same as rocket thrust is asserting that the
>HS> rotor blades' L/D is around 1. But at subsonic speeds,
>HS> the L/D of a good airfoil design is more like 100...
>
>..for the best gliders
No, for the *airfoil* -- the lifting surface itself, helicopter blades
being almost pure lifting surfaces. The L/D of an *aircraft* is always
rather less than that of its wing, because parts like the fuselage add
drag but generally don't add significant lift. (There are also losses
associated with finite airfoil length, which affect both aircraft and
helicoper blades.)
>HS> ...Various complications
>HS> intervene if the air is already moving rapidly past you,
>HS> but at low speeds, using a rotor wins big over a rocket.
>
>We are talking about a helicopter that has enough thrust to
>lift a rocket launcher. Suppose that the total rotor area
>of the helicopter is 10^4 m^2 = one hectare -- a pretty big
>helicopter. If the launcher weighs 100 tons and it is lifted
>to the altitude of 30 km... Are you suggesting to make a
>helicopter having the total rotor area much bigger than one
>hectare?
Note that you're going to need not just a pretty big helicopter, but a
huge one, to meet this requirement -- an enormous load (by helicopter
standards) lifted to extremely high altitude (by the standards of any
aircraft type, let alone helicopters, which are low-altitude vehicles).
Your requirement inherently calls for a vast rotor area.
(And it is *your* requirement, not mine. I'm not the one advocating
helicopter launch, or indeed air launch of any kind -- I'm just trying to
correct some misconceptions about the aerodynamics involved.)
>...You cannot get much bigger
>lift-to-drag ratio than one when the air moves down at the
>speed of 100 meters per second...
If you assume that the air is *entering* the rotor at 100m/s, then it is
indeed rather difficult to achieve high L/D with an open propellor/rotor.
But you have not justified that assumption. The fact that you can sketch
a badly-designed helicopter doesn't mean that well-designed ones are
impossible.
>...good argument in favor of using an airplane propelled
>by small rocket engine instead of the helicopter propelled
>by the hydrogen peroxide turbines.
Or better yet, just use a rocket. Not an airplane, a rocket. Rockets are
simple, compact, and well understood, and they reach 30km altitudes with
ease, which is not true of *any* type of aircraft.
>Does anyone really need big, monolithic satellites and big
>rocket launchers? It seems that satellites of any size can be
>assembled in orbit by telemanipulators.
That's an interesting theory, to date completely unsupported by actual
demonstrated results. (The robotics guys I know would probably ask what
you've been drinking.) The proven way to do orbital assembly is with
people, not robots, doing the work.
Derek Lyons
>>Does anyone really need big, monolithic satellites and big
>>rocket launchers? It seems that satellites of any size can be
>>assembled in orbit by telemanipulators.
>
>That's an interesting theory, to date completely unsupported by actual
>demonstrated results. (The robotics guys I know would probably ask what
>you've been drinking.) The proven way to do orbital assembly is with
>people, not robots, doing the work.
I note that *he* said telemanipulators, *you* said robots. The two
are not quite the same thing.
D.
--
Touch-twice life. Eat. Drink. Laugh.
Henry Spencer
>But I suppose that's one of the bits of precious IP left over from the
>company's demise, and it is sitting in somebody's drawer, doing no one
>any good right now.
If memory serves, XCOR bought the remaining propulsion-related IP from
Rotary. XCOR being XCOR, they didn't do that just because they were tired
of not being able to discuss it in public, so they at least hope it *will*
do them some good... but it may be long-term.
Henry Spencer
Derek Lyons <fair...@gmail.com> wrote:
>>>...It seems that satellites of any size can be
>>>assembled in orbit by telemanipulators.
>>That's an interesting theory, to date completely unsupported by actual
>>demonstrated results. (The robotics guys I know would probably ask what
>>you've been drinking.) The proven way to do orbital assembly is with
>>people, not robots, doing the work.
>
>I note that *he* said telemanipulators, *you* said robots. The two
>are not quite the same thing.
The terminology is not reliably precise enough to make such fine
distinctions; the robotic hardware in question is all teleoperated.
(Some of the robotics guys in question worked on the exact hardware
he thinks is so miraculous. It's not.)
Derek Lyons
>In article <cdstnc$1td$1...@new7.xnet.com>, James Graves <ans...@xnet.com> wrote:
>>But I suppose that's one of the bits of precious IP left over from the
>>company's demise, and it is sitting in somebody's drawer, doing no one
>>any good right now.
>
>If memory serves, XCOR bought the remaining propulsion-related IP from
>Rotary. XCOR being XCOR, they didn't do that just because they were tired
>of not being able to discuss it in public, so they at least hope it *will*
>do them some good... but it may be long-term.
XCOR is very openly and explicitly (along with Armadillo) in the game
for the long haul.